1. Field of the Invention
The present invention relates to a liquid ejection head and a liquid ejection apparatus that eject liquid.
2. Description of the Related Art
In an inkjet recording apparatus serving as a typical liquid ejection apparatus, an off-carriage system and an on-carriage system are used to supply ink to an inkjet head. In an off-carriage system, an inkjet head is provided with a portion that stores ink (hereinafter also referred to as a sub-tank), via which ink is supplied to the inkjet head from an ink tank that is not mounted on a carriage (hereinafter also referred to as a main tank). In contrast, in an on-carriage system, an ink tank is mounted together with an inkjet head on a carriage, and ink is supplied from the ink tank to the inkjet head, not via a sub-tank.
When a large number of ink colors are used, or when a large-capacity ink tank is used, heavy weight is put on the carriage in the on-carriage system. In such a case, it is more advantageous to use the off-carriage system.
One way to supply ink from the main tank to the inkjet head in the off-carriage system is to use an ink supply tube that is connected at one end to the main tank and at the other end to the inkjet head. The ink supply tube and the inkjet head are connected by their respective joint portions (connecting portions). In this case, if the joint portion of the tube and the joint portion of the head are connected although they are misaligned, ink leakage may occur at the joint portions. For this reason, it is necessary to position the joint portions accurately.
Japanese Patent Laid-Open No. 2004-74782 discloses a structure for positioning joint portions. In this disclosed structure, as illustrated in FIG. 10, a first member has two positioning pins, and a second member 89 has a circular hole 89d and a slotted hole 89e at positions corresponding to the two positioning pins of the first member. The positioning pins and the holes are fitted together to form positioning portions, which determine the relative position between the members.
Recent inkjet recording apparatuses intended to print photographs sometimes use multiple ink colors in order to realize high image quality. Correspondingly, the number of ink supply tubes and the number of joint portions (connecting portions) to be connected to the ink supply tubes increase. When the number of joint portions is large, a joint portion area where the joint portions are arranged is wide. In general, as the size of a component increases, it becomes more difficult to increase the dimensional accuracy. Thus, the dimensional tolerance of the component increases. Therefore, as the joint portion area is widened, the distances from the positioning portions to the joint portions increase, and the dimensional tolerance also increases. If a sufficient positioning accuracy is not ensured, ink leakage may occur at the joint portions. However, a sufficient consideration has not hitherto been given to the positional accuracy for a large number of joint portions.